Feature History for G.722-64 and iLBC Codec Support on Cisco Unified Communications Manager Express

Release

Modification

12.4(15)XZ

This feature was introduced.

15.0(1)M

This feature was integrated into Cisco IOS Release 15.0(1)M.

Feature History for G.722-64 and iLBC Codec Support on Cisco UBEs, DSP Farms, and Voice Gateways

Release

Modification

12.4(15)XY

This feature was introduced.

15.0(1)M

This feature was integrated into Cisco IOS Release 15.0(1)M.

Feature History for Universal Voice Transcoding Support for Cisco Unified Border Elements

Release

Modification

12.4(11)XY

This feature was introduced.

15.0(1)M

This feature was integrated into Cisco IOS Release 15.0(1)M.

Feature History for Out-of-Band to In-Band DTMF Relay for Voice Gateway Routers

Release

Modification

12.3(8)XY

This feature was introduced.

12.3(11)T

This feature was integrated into Cisco IOS Release 12.3(11)T.

12.3(14)T

Support was added for the PVDM2 on the Cisco 2800 series and Cisco 3800 series voice gateway routers.

Feature History for Enhanced Conferencing and Transcoding for Voice Gateway Routers

Release

Modification

12.3(8)T

This feature was introduced for the NM-HDV2, NM-HD-1V, NM-HD-2V, and NM-HD-2VE.

12.3(11)T

Support was added for the PVDM2 on the Cisco 2800 series and Cisco 3800 series voice gateway routers.

Feature History for Conferencing and Transcoding for Voice Gateway Routers

Release

Modification

12.1(5)YH

This feature was introduced for the NM-HDV-FARM on the Cisco VG200.

12.2(13)T

This feature was integrated into Cisco IOS Release 12.2(13)T and support was added for the NM-HDV on the Cisco 2600 series, Cisco 3600 series, Cisco 3700 series, and Cisco VG200.

12.3(2)XE

Support was added for the PVDM-256K on the Cisco 1751, Cisco 1751-V, and Cisco 1760.

12.3(8)T

Support for the PVDM-256K on the Cisco 1751, Cisco 1751-V, and Cisco 1760 was integrated into Cisco IOS Release 12.3(8)T.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

For more information about this and related Cisco IOS voice features, see the following:

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Conferencing and Transcoding for Voice Gateway Routers

DSP Resources

The router must be equipped with one or more of the following network modules or voice DSP modules to provide DSP resources for conferencing, transcoding, and hardware MTP services:

Cisco Unified Communications Manager and Cisco IOS Release

Minimum software requirements for type of network or voice module:

Module

Cisco Unified Communications Manager version

Cisco IOS Release

NM-HDV2,NM-HD-1V/2V/2VE

Cisco Unified Communications Manager 3.3(4) (formerly known as Cisco CallManager 3.3(4)) or later for conferencing and transcoding, Cisco Unified Communications Manager 4.0(1) (formerly known as Cisco CallManager 4.0(1)) or later for MTP

Cisco IOS Release 12.3(8)T or later

PVDM2(Cisco 2800 series)

Cisco Unified Communications Manager 3.3(5) (formerly known as Cisco CallManager 3.3(5)) or later for conferencing and transcoding, Cisco Unified Communications Manager 4.0(2a) (formerly known as Cisco CallManager 4.0(2a)) or later for MTP

Cisco IOS Release 12.3(8)T4 or later

PVDM2(Cisco 3800 series)

Cisco Unified Communications Manager 3.3(5) (formerly known as Cisco CallManager 3.3(5)) or later for conferencing and transcoding, Cisco Unified Communications Manager 4.0(2a) (formerly known as Cisco CallManager 4.0(2a)) or later for MTP

Cisco IOS Release 12.3(11)T or later

NM-HDV

Cisco Unified Communications Manager 3.2(2c) (formerly known as Cisco CallManager 3.2(2c)) or later

Cisco IOS Release 12.2(13)T or later

Conference bridge, transcoder, and MTP services must be configured in Cisco Unified Communications Manager. See the following chapters in the Cisco Unified Communications Manager Administration Guide :

DSP farm services cannot be enabled for a slot on the Cisco 1700 series so the dspservicesdspfarm command is not supported and cannot be configured for a voice card on the Cisco 1700 series.

Conferencing is not supported on a Cisco 3640 using the NM-HD-1V, NM-HD-2V, or NM-HD-2VE.

Simultaneous use of DSP farm services on the NM-HDV and NM-HDV2 is not supported.

Hardware MTPs are not supported on the NM-HDV or NM-HDV-FARM.

Hardware MTPs support only G.711 a-law and G.711 u-law. If you configure a profile as a hardware MTP, and you want to change the codec to other than G.711, you must first remove the hardware MTP by using the nomaximumsessionshardware command.

Software MTPs are supported on the NM-HDV only if the dspservicesdspfarmcommand is not enabled on the voice card.

Only one codec is supported for each MTP profile. To support multiple codecs, you must define a separate MTP profile for each codec.

If an MTP call is received but MTP is not configured, transcoding is used if resources are available.

Dynamic conference and transcoding resource allocation is not supported.

Fax is not supported for transcoding.

Information About Conferencing and Transcoding for Voice Gateway Routers

To configure Cisco conferencing and transcoding, you should understand the following concepts:

DSP Farms

A DSP farm is the collection of DSP resources available for conferencing, transcoding, and MTP services. DSP farms are configured on the voice gateway and managed by Cisco Unified Communications Manager through Skinny Client Control Protocol (SCCP).

The DSP farm can support a combination of transcoding sessions, MTP sessions, and conferences simultaneously. The DSP farm maintains the DSP resource details locally. Cisco Unified Communications Manager requests conferencing or transcoding services from the gateway, which either grants or denies these requests, depending on resource availability. The details of whether DSP resources are used, and which DSP resources are used, are transparent to Cisco Unified Communications Manager.

DSP Farm Profiles

DSP-farm profiles are created to allocate DSP-farm resources. Under the profile you select the service type (conference, transcode, MTP), associate an application, and specify service-specific parameters such as codecs and maximum number of sessions. A DSP-farm profile allows you to group DSP resources based on the service type. Applications associated with the profile, such as SCCP, can use the resources allocated under the profile. You can configure multiple profiles for the same service, each of which can register with one Cisco Unified Communications Manager group. The profile ID and service type uniquely identify a profile, allowing the profile to uniquely map to a Cisco Unified Communications Manager group that contains a single pool of Cisco Unified Communications Manager servers.

Conferencing

Voice conferencing involves adding several parties to a phone conversation. In a traditional circuit-switched voice network, all voice traffic passes through a central device such as a PBX. Conference services are provided within this central device. In contrast, IP phones normally send voice signals directly between phones, without the need to go through a central device. Conference services, however, require a network-based conference bridge.

In an IP telephony network using Cisco Unified Communications Manager, the Conferencing and Transcoding for Voice Gateway Routers feature provides the conference-bridging service. Cisco Unified Communications Manager uses a DSP farm to mix voice streams from multiple participants into a single conference-call stream. The mixed stream is played out to all conference attendees, minus the voice of the receiving attendee.

Meet me--Participants call in to a central number and are joined in a single conference.

Participants whose end devices use different codec types are joined in a single conference; no additional transcoding resource is needed.

This feature provides voice conferencing at the remote site, without the need for access to the central site (see the figure below).

Figure 1

Conferencing Service

Transcoding

Transcoding compresses and decompresses voice streams to match endpoint-device capabilities. Transcoding is required when an incoming voice stream is digitized and compressed (by means of a codec) to save bandwidth, but the local device does not support that type of compression. Ideally, all IP telephony devices would support the same codecs, but this is not the case. Rather, different devices support different codecs.

Transcoding is processed by DSPs on the DSP farm; sessions are initiated and managed by Cisco Unified Communications Manager which also refers to transcoders as hardware MTPs.

This feature provides transcoding at the remote site, without the need for access to the central site (see the figure below).

Figure 2

Transcoding Service

Media Termination Point

A Media Termination Point (MTP) bridges the media streams between two connections allowing Cisco Unified Communications Manager to relay calls that are routed through SIP or H.323 endpoints.

The following MTP resources are supported for Cisco Unified Communications Manager 4.0 (formerly known as Cisco CallManager 4.0) and later releases:

Software MTP--Software-only implementation that does not use a DSP resource for endpoints using the same codec and the same packetization time.

Hardware MTP--Hardware-only implementation that uses a DSP resource for endpoints using the same G.711 codec but a different packetization time. The repacketization requires a DSP resource so it cannot be done by software only. Cisco Unified Communications Manager also uses the term software MTP when referring to a hardware MTP.

Transcoder as MTP--Implementation that uses a DSP resource for endpoints using the same G.711 codec (on both legs) or a mixture of different supported codecs. This functionality is used by Cisco Unified Communications Manager to view the transcoders as usable MTP resources (if they are available in the pool) and enables Cisco Unified Communications Manager to use MTP resources more effectively when a call is deemed to use a transcoder and an MTP resource at the same time.

For MTP and transcoding, the DSP farm supports only two IP streams connected to each other at a time. If more than two streams need connecting, the streams must be connected using conferencing.

Conferencing and Transcoding Features on the NM-HDV2 and NM-HD-1V 2V 2VE

Conferencing

Cisco Unified Communications Manager meet-me and ad-hoc conferences with up to eight participants each

Up to 50 eight-party conferences on a single NM-HDV2, up to 24 eight-party conferences on a single NM-HD-2VE, and up to 8 eight-party conferences on a single NM-HD-1V/2V

Participants using G.711 and G.729 codecs joined in a single conference; no additional transcoding resources are needed to include the disparate codec types

Easy deployment of conference resources in routers across the network, reducing WAN use and improving voice-network performance

Allocation of DSP Resources Within the Voice Network Module

You allocate DSP resources either to voice termination of the voice trunk group or to the DSP farm. Occasionally these allocations can conflict.

If you previously allocated DSP resources to voice termination and you now try to configure a DSP farm, you might find that insufficient DSP resources are available. Conversely, if you previously allocated DSP resources to a DSP farm and you now try to configure a trunk group, you might find that insufficient DSP resources are available.

If your requested configuration is rejected, you have two options:

Insert more DSPs on the voice network module (NM-HDV or NM-HDV2)

Allocate a different voice network module for either the DSP farm or the trunk group

Allocation of DSP Resources Within the DSP Farm

You should know the following about your system:

Number of DSPs required to handle your anticipated number of conference calls and transcoding sessions

Number of DSPs that your system can support

DSP resources can reside in packet-voice DSP modules (PVDMs) installed in voice network modules, for example the NM-HDV2, or directly in the network module, for example the NM-HD-2V. Cisco 2800 series and 3800 series voice gateway routers have onboard DSP resources located on PVDM2s installed directly on the motherboard. Your router supports one or more voice network modules.

The table below lists the total DSPs that are supported on a fully-loaded voice network module.

Table 1

Total DSPs Supported Per Voice Network Module

Network Module

Maximum DSPs per PVDM2/PVDM

Maximum PVDM2s/PVDMs per Network Module

Maximum DSPs

NM-HDV2

4

4

16

NM-HD-1V/2V

--

--

1

NM-HD-2VE

--

--

3

NM-HDV

3

5

15

The table below lists the total number of network modules that are supported per router.

3 Although the chassis has a slot for an additional module, it cannot operate with more than the specified number.
4 Provided processor resources are available.

Conferencing and Transcoding Session Capacities

Each DSP is individually configurable to support either conferencing or transcoding and standard voice termination. The total number of conferencing, transcoding, and voice termination sessions is limited by the capacity of the entire system, which includes the DSPs, hardware platform, physical voice interface, and Cisco Unified Communications Manager.

The tables below list the maximum number of conference calls and transcoding sessions that DSPs can handle, in theory. Actual capacity may be less based on the total system design.

Table 3

DSP Theoretical Session Capacities

Application

NM-HD-1V/2V (1 DSP)

NM-HD-2VE (3 DSPs)

NM-HDV2 (16 DSPs)

2801/2811 (2 PVDM2-64)

2821/2851 (3 PVDM2-64)

3825, 3845 (4 PVDM2-64)

Conferencing

G.711

8 sessions (64 conferees)

24 sessions (192 conferees)

50 sessions (400 conferees)

50 sessions (400 conferees)

50 sessions (400 conferees)

50 sessions (400 conferees)

G.722-64

2 sessions (16 conferees)

6 sessions (48 conferees)

32 sessions (256 conferees)

16 sessions (128 conferees)

24 sessions (192 conferees)

32 sessions (256 conferees)

G.729

2 sessions (16 conferees)

6 sessions (48 conferees)

32 sessions (256 conferees)

16 sessions (128 conferees)

24 sessions (192 conferees)

32 sessions (256 conferees)

GSM FR

--

2 sessions (16 conferees)

14 sessions (112 conferees)

7 sessions (56 conferees)

10 sessions (80 conferees)

14 sessions (112 conferees)

GSM EFR

--

1 session (8 conferees)

10 sessions (80 conferees)

5 sessions (40 conferees)

8 sessions (64 conferees)

10 sessions (80 conferees)

iLBC

1 session (8 conferees)

3 sessions (24 conferees)

16 sessions (128 conferees)

8 sessions (64 conferees)

12 sessions (96 conferees)

16 sessions (128 conferees)

Transcoding

G.711 a-law/u-law <-> any (with high complexity codec in dspfarmprofile)

6 sessions

18 sessions

96 sessions

48 sessions

72 sessions

96 sessions

G.711 a-law/u-law <-> any (without high complexity codec in dspfarmprofile)

NM-HDV System Capacities

The table below lists the number of transcoding sessions and conference calls supported on the NM-HDV.

Table 5

NM-HDV Theoretical System Capacities

Device

Capacity

A single DSP

4 transcoding sessions

1 conference call with up to 6 participants

A single PVDM (3 DSPs)

12 transcoding sessions

3 conference calls, each with up to 6 participants, for a total of up to 18 participants

A fully loaded NM-HDV (5 PVDMs holding 15 DSPs)

60 transcoding sessions

15 concurrent conference calls, each with up to 6 participants, for a total of up to 90 participants

Use the following tables to determine the number of PVDMs required to support your DSP needs and whether your router is capable of holding enough NM-HDVs to accommodate these PVDMs:

See the table below if you use either of the following:

20-, 30-, 40-, 50-, or 60-ms packetization

10-ms packetization with voice-activity detection (VAD) enabled

See the table beneath the table below if you use 10-ms packetization with VAD disabled

Note

Numbers in the following table represent the number of PVDMs required within a single NM-HDV or NM-HDV-FARM to support the desired configuration. Where numbers are not given, the configuration is not possible using a single NM-HDV.

Numbers given in the following table represent the number of PVDMs required within a single NM-HDV to support the desired configuration. Where numbers are not given, the configuration is not possible using a single NM-HDV.

Table 7

PVDM Requirements Using 10-ms Packetization and with VAD Disabled

Transcoding Sessions

Conference Calls

0

1

2

3

4

5

6

7

8

9

10

0

--

1

1

1

2

2

2

3

3

3

4

1-4

1

1

1

2

2

2

3

3

3

--

--

5-8

1

1

2

2

2

3

3

3

--

--

--

9-12

1

2

2

2

3

3

3

--

--

--

--

13-16

2

2

2

3

3

--

--

--

--

--

--

17-20

2

2

3

3

--

--

--

--

--

--

--

21-24

2

3

3

--

--

--

--

--

--

--

--

25-28

3

--

--

--

--

--

--

--

--

--

--

29-30

3

--

--

--

--

--

--

--

--

--

--

How to Configure Conferencing and Transcoding for Voice Gateway Routers

Determining DSP Resource Requirements

DSPs reside either directly on a voice network module, such as the NM-HD-2VE, on PVDM2s that are installed in a voice network module, such as the NM-HDV2, or on PVDM2s that are installed directly onto the motherboard, such as on the Cisco 2800 and 3800 series voice gateway routers. You must determine the number of PVDM2s or network modules that are required to support your conferencing and transcoding services and install the modules on your router.

SUMMARY STEPS

1. Determine the number of transcoding sessions and conference calls that your router must support.

2. Determine the number of DSPs that are required to support the transcoding sessions and conference calls. If voice termination is also required, determine the additional DSPs required.

3. Determine the maximum number of network modules that your router can support.

Configuring a DSP Farm Profile

Perform this procedure to define a DSP farm on the NM-HDV2, NM-HD-1V, NM-HD-2V, NM-HD-2VE, or PVDM2. You must configure each conferencing, transcoding, and MTP profile separately.

Note

Because a software-only MTP does not require DSP resources, you can configure a software-only MTP without a voice network module, or on the NM-HDV if you do not enable the dspservicesdspfarmcommand for the voice card.

Before You Begin

Requires Cisco IOS Release 12.3(8)T or a later release. Universal transcoding requires Cisco IOS Release 12.4(11)XY or a later release.

The profile-identifier and service type uniquely identifies a profile. If the service type and profile-identifier pair is not unique, you are prompted to choose a different profile-identifier .

Step 7

descriptiontext

Example:

Router(config-dspfarm-profile)# description art_dept

(Optional) Includes a specific description about the Cisco DSP farm profile.

Step 8

codeccodec-type

Example:

Router(config-dspfarm-profile)# codec ilbc

Specifies the codecs supported by a DSP farm profile.

Repeat this step for each codec supported by the profile.

Note

Hardware MTPs support only G.711 a-law and G.711 u-law. If you configure a profile as a hardware MTP, and you want to change the codec to other than G.711, you must first remove the hardware MTP by using the nomaximumsessionshardware command.

Note

Only one codec is supported for each MTP profile. To support multiple codecs, you must define a separate MTP profile for each codec.

Step 9

maximumsessions {hardware | software} number

Example:

Router(config-dspfarm-profile)# maximum sessions 4

Specifies the maximum number of sessions that are supported by the profile.

number --Range is determined by the available registered DSP resources. Default is 0.

(Optional) Specifies the amount of time that a DSP farm profile waits before attempting to connect to another Cisco Unified Communications Manager when the current Cisco Unified Communications Manager fails to connect.

seconds --Range is 1 to 3600. Default is 60.

Step 5

connectretriesnumber

Example:

Router(config-sccp-ccm)# connect retries 5

(Optional) Specifies the number of times that a DSP farm attempts to connect to a Cisco Unified Communications Manager when the current Cisco Unified Communications Manager connections fails.

number --Range is 1 to 32. Default is 3.

Step 6

keepaliveretriesnumber

Example:

Router(config-sccp-ccm)# keepalive retries 7

(Optional) Sets the number of keepalive retries from SCCP to the Cisco Unified Communications Manager.

number --Range is 1 to 32. Default is 3.

Step 7

keepalivetimeoutseconds

Example:

Router(config-sccp-ccm)# keepalive timeout 50

(Optional) Sets the number of seconds between keepalive messages from SCCP to the Cisco Unified Communications Manager.

seconds --Range is 1 to 180. Default is 30.

Step 8

registrationretriesretry-attempts

Example:

Router(config-sccp-ccm)# registration retries 15

(Optional) Sets the number of registration retries that SCCP tries to register with the Cisco Unified Communications Manager.

retry-attempts --Range is 1 to 32. Default is 3.

Step 9

registrationtimeoutseconds

Example:

Router(config-sccp-ccm)# registration timeout 8

(Optional) Sets the number of seconds between registration messages sent from SCCP to the Cisco Unified Communications Manager.

seconds --Range is 1 to 180. Default is 3.

Step 10

switchovermethod {graceful | immediate}

Example:

Router(config-sccp-ccm)# switchover method graceful

(Optional) Sets the switchover method that the SCCP client uses when the communication link to the active Cisco Unified Communications Manager fails.

Verify that the VoIP dial peer application exists on the terminating gateway.

Collect relevant information from debug and show commands, and configuration files before contacting Cisco Technical Support for assistance.

You can clear any of the following by disabling the DSP farm or SCCP:

Active calls

DSPs

Active connection to a Cisco Unified Communications Manager

MTP Troubleshooting Tips

MTP profiles can use only G.711 a-law or G.711 u-law. If you define a profile for a hardware MTP, and you want to change the codec to other than G.711, you must first remove the hardware MTP by using the nomaximumsessionshardware command.

Verify that only one codec is assigned for each MTP profile. To support multiple codecs, you must define a separate MTP profile for each codec.

Troubleshooting DSP-Farm Services

You can troubleshoot performance by performing any of the following steps.

SUMMARY STEPS

1.debugsccp {all | errors | events | packets | parser}

2.debugdspfarm {all | errors | events | packets}

3.debugmediaresourceprovisioning {all | errors| events}

DETAILED STEPS

Command or Action

Purpose

Step 1

debugsccp {all | errors | events | packets | parser}

Example:

Router# debug sccp all

(Optional) Sets debugging levels for SCCP and its applications.

Step 2

debugdspfarm {all | errors | events | packets}

Example:

Router# debug dspfarm all

(Optional) Sets debugging levels for DSP-farm service.

Step 3

debugmediaresourceprovisioning {all | errors| events}

Example:

Router# debug media resource provisioning all

(Optional) Sets debugging levels for media resource provisioning.

Configuring Conferencing and Transcoding (NM-HDV)

Perform the following procedures to configure enhanced conferencing and transcoding on the NM-HDV.

Configuring the DSP Farm on the NM-HDV

Perform this task to configure a DSP farm on an NM-HDV.

Note

If you configured a DSP farm in Cisco IOS Release 12.1(5)YH and have now upgraded to Cisco IOS Release 12.2(13)T or later, you must reconfigure the DSP farm, including enabling DSP-farm services on the NM-HDV and specifying maximum session numbers in each category as appropriate. Your previous configuration no longer works.

SUMMARY STEPS

1.enable

2.configureterminal

3.voice-cardslot

4.dspservicesdspfarm

5.exit

6.dspfarmconfbridgemaximumsessionsnumber

7.dspfarmtranscodermaximumsessionsnumber

8.dspfarm

9.exit

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password when prompted.

Step 2

configureterminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

voice-cardslot

Example:

Router(config)# voice-card 1

Enters voice-card configuration mode for the network module on which you want to enable DSP-farm services.

Step 4

dspservicesdspfarm

Example:

Router(config-voicecard)# dsp services dspfarm

Enables DSP-farm services on the voice card.

Step 5

exit

Example:

Router(config-voicecard)# exit

Returns to global configuration mode.

Step 6

dspfarmconfbridgemaximumsessionsnumber

Example:

Router(config)# dspfarm confbridge maximum sessions 3

Specifies the maximum number of conferencing sessions to be supported by the DSP farm. A DSP can support 1 conference session with up to 6 participants.

Note

When you assign this value, take into account the number of DSPs allocated for transcoding services.

Step 7

dspfarmtranscodermaximumsessionsnumber

Example:

Router(config)# dspfarm transcoder maximum sessions 12

Specifies the maximum number of transcoding sessions to be supported by the DSP farm. A DSP can support up to 4 transcoding sessions.

Note

When you assign this value, take into account the number of DSPs allocated for conferencing services.

Consider your system requirements when configuring DSP farms and SCCP because the defaults for some commands might not result in expected behavior. In particular, the correct settings for the following commands are platform-specific and depend on your individual network characteristics:

connectinterval

connectretries

keepaliveretries

keepalivetimeout

sccpregistrationretries

sccpregistrationtimeout

switchbackinterval

Restrictions

Multifrequency is supported by MTPs but Cisco Unified Communications Manager does not support it.

Software MTP supports G.711 codecs only.

Out-of-Band to In-Band DTMF Relay for Cisco IOS Voice Gateways

The Out-of-Band to In-Band DTMF Relay for Cisco IOS Voice Gateways feature provides the event processing capability in RFC 2833 that enables DTMF relay communication between SIP devices and nonSIP endpoints using Cisco Unified Communications Manager. RFC 2833 defines a method of transporting tones and other telephony events over Real-Time Transport Protocol (RTP) to ensure DTMF digits are accurately transmitted in a packet environment. A single packet representing a DTMF tone as an event code is passed within an RTP audio stream instead of sending the DTMF tone in-band, where it could be corrupted because of packet loss. When the packet reaches the receiver, it re-creates a tone of the correct frequency and duration.

DTMF detection and generation capabilities are added to the hardware and software MTP. The MTP generates out-of-band SCCP events to Cisco Unified Communications Manager when it detects a DTMF tone. The MTP creates event packets for DTMF digits and inserts the packets into the outgoing RTP stream after receiving an SCCP request from Cisco Unified Communications Manager.

The figure below illustrates the media setup and DTMF tone flow between a SIP network and nonSIP network over a DSP farm MTP.

Figure 3

DTMF Tone Flow Between a SIP and NonSIP Network

This feature supports DTMF relay using the following MTP and transcoder resources for Cisco Unified Communications Manager 4.0 (formerly known as Cisco CallManager 4.0):

Software MTP--Software-only implementation that does not use a DSP resource for endpoints using the same codec and the same packetization time.

Hardware MTP--Hardware-only implementation that uses a DSP resource for endpoints using the same G.711 codec but a different packetization time. Cisco Unified Communications Manager refers to it also as a software MTP.

Transcoder--Hardware-only implementation using a DSP resource for endpoints using different codecs. Cisco Unified Communications Manager also refers to it as a hardware MTP.

For MTP and transcoding, the DSP farm supports only two IP streams connected to each other at a time. If more than two streams need connecting, the streams must be connected using conferencing.

DSP-Farm Services on the NM-HDV2 or PVDM2 Example

The following example shows a configuration of conferencing and transcoding services on an NM-HDV2 or PVDM2. DSP farm profile 6, which supports transcoding, and profile 10, which supports conferencing are both assigned to Cisco Unified Communications Manager group 988.

Universal Transcoding with an Inbox on a Universal Gateway Example

The following example shows a universal transcoding configuration with an inbox on a Cisco Unified Border Element on a universal gateway. Universal gateways include the Cisco AS5350XM and Cisco AS5400XM platforms:

G.711 to Any Transcoding with an Inbox on a Universal Gateway Example

The following example shows the configuration for transcoding for G.711 to any codec with an inbox on a Cisco Unified Border Element on a universal gateway. Universal gateways include the Cisco AS5350XM and Cisco AS5400XM platforms:

Universal and G.711 to Any Transcoding with an Inbox on a Universal Gateway Example

The following example shows the configuration for transcoding for both universal and G.711 to any codec with an inbox on a Cisco Unified Border Element on a universal gateway. Universal gateways include the Cisco AS5350XM and Cisco AS5400XM platforms:

Universal and G.711 to Any Transcoding with an Inbox on an ISR Example

The following example shows the configuration for transcoding for both universal and G.711 to any codec with an inbox on a Cisco Unified Border Element on an integrated services router. Integrated services routers include the Cisco 2800 and Cisco 3800 platforms:

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